Yol. 67.] WEST, MID, AND EAST SOMERSET. 25 



pieces of close-grained compact limestone, thereby indicating a slight 

 non-sequence. Bristow & Etheridge noticed this rubbly condition 

 of the bottom part of the Sun-Bed in their record. 



I have indicated the place where I should expect to find the 

 Cotham Marble if a longer search had been possible. The horizon 

 pointed out is somewhat lower than that occupied by the stratum 

 suggested by the Geological Survey officers as its probable equiva- 

 lent. As showing that the suggestion, that a continuous stratum 

 •such as they indicate is the equivalent of the Cotham Marble, is 

 improbable, it may be remarked that in Mid and West Somerset 

 the equivalent of the Cotham Marble is generally an intermittent 

 layer of nodules — not a continuous limestone-bed. 



A very interesting feature about this St. Audrie's-Slip section is 

 the peculiar arrangement of the deposits in the neighbourhood of 

 the junction of the Langport and Cotham Beds. At the base of the 

 former division is Bed 4 (3) b : it is remarkably persistent, and there- 

 fore constitutes a good datum-level. But, while in one place it rests 

 directly upon the Pteria-contorta Shales, in another it is separated 

 therefrom by a greenish marl 22 inches thick [Bed 4 (3) c]. 



At this horizon, at Charlton-Mackrell (p. 42) and Sparkford- 

 Hill (p. 48) railway-cuttings, occur those remarkable boulder-like 

 masses of limestone which themselves are indicative of disturbed 

 conditions of sedimentation. Here at St. A udrie's Slip is evidence 

 pointing in the same direction, and these facts considered together 

 .afford some explanation of the circumstance that the Pteria-contorta 

 Shales, with their well-known blackness, give place comparatively 

 so suddenly to the pale marls and limestones of the Cotham Beds, 

 which had obviously a very different history. 



Bed 5 b is again easily found — its hard nodules being covered 

 with well-preserved fossils. Species of Actceonina and Natica oppeli 

 Moore are particularly abundant. 



The Pleurophorus Bed is richly fossiliferous when found ; but 

 the same cannot be said for the Bone-Bed. This bed is somewhat 

 disappointing, and totally unlike its equivalent stratum farther 

 west near Blue Anchor. It is a conglomeratic rock, consisting of 

 subangular pieces of grey-blue limestone embedded in a greenish, 

 siliceous, and earthy brown matrix — the greenish siliceous and 

 micaceous matter also forming an almost pure layer at the base. 



The Westbury Beds below stratum 17, with the exception of 

 the basal bone-bed, were not well-exposed when I visited the 

 locality, and so I have had to rely upon Bristow & Etheridge's 

 figures for the thicknesses of the deposits intervening between 

 Bed 17 and the Sully Beds. The basal bone-bed is very similar to 

 that which occupies an equivalent position all along the coast to the 

 west of Watchet and between that locality and Blue Anchor; but 

 vertebrate-remains are not quite so numerous here. 



A noticeable feature about the Keuper is the scarcity (if not 

 absence) of layers of gypsum, which are so numerous at Blue- 

 Anchor Point. Between the base of the Pteria-contorta Shales and 

 the top of the red marls (Keuper) intervenes — according to Bristow 



